1. Field of the Invention
The present invention relates to an antenna for a portable communication device.
2. Description of the Related Art
It is known that a circular disc monopole antenna using a circular antenna component obtains wideband characteristics. A circular disc monopole antenna having a circular antenna component modified for miniaturization is disclosed in Japan Patent Laid-Open Publication No. 2002-164731, which discloses the circular antenna component bent perpendicularly with respect to its diameter.
In conventional portable communication devices, however, the antenna component occupies a large area and the antenna needs to be further scaled down. For example, there is very limited room for securing an antenna in small communication devices. Thus, small-size antennas are required.
Moreover, the use of a conventional modified circular antenna component causes an anti-resonant point in a desired frequency band, thereby deteriorating Voltage Standing Wave Ratio (VSWR) characteristics and making it difficult to maintain constant wideband characteristics.